Address code terminal

ABSTRACT

An identification circuit for use in a remote unit, such as a data terminal, is disclosed. The circuit includes a matrix assembled on a printed circuit board and associated logic means. The matrix includes a series of strips having holes. Message programming is accomplished by inserting a diode between corresponding holes of two strips to achieve proper row-column connections. The logic means causes a signal to be applied to the rows of the matrix, one at a time, and the signal appearing at the columns is the desired identification signal. One of the matrix columns is assigned to a stop bit and when this stop bit is detected, the logic means ceases applying the signals to the matrix rows and indicates that the identification message is completed.

United States Patent [191 Moses Jan. 29, 1974 ADDRESS CODE TERMINAL Primary Examiner-Harold I. Pitts I Attorney, Agent, or Firm-J. T. Cavender; Wi bert [75] Inventor. Eonald J. Moses, Ketteringi Ohio Hawk Jr; John J Callahan [73] Assignee: he National Cash Register Company, Dayton, Ohio [57] ABSTRACT An identification circuit for use in a remote unit, such [22] Flled' 1972 as a data terminal, is disclosed. The circuit includes a 21 Appl. No.: 235,597

matrix assembled on a printed circuit board and associated logic means. The matrix includes a series of strips having holes. Message programming is accom- [Z] 81. 340/166 R, 330/ 163 /1013 pushed by inserting a diode between corresponding I d 5 1 64 R holes of two strips to achieve proper row-column con- I 0 nections. The logic means causes a signal to be ap- 56 R f d plied to the rows of the matrix, one at a time, and the I 1 e erences signal appearing at the columns is the desired identifi- UNITED STATES PATENTS cation signal. One of the matrix columns is assigned to 2,610,243 9/1952 Burkhart 340/365 S a stop bit and when this stop bit is detected, the logic 3,064,236 11/1962 Co m 0/ I6 R means ceases applying the signals to the matrix rows 3,171,098 2/ 1965 340/166 X and indicates that the identification message is com- 3,230,355 1/1966 Chu 340/164 X pleted 3,281,795 10/1966 Gural 340/164 X 10 Claims, 8 Drawing Figures I8 19 OUTPUT I 2 4 CIRCUIT KEYBOARD INTERFACE ['6 KEYBOARD CLOCK LOGIC T PRINTER ENQ Ell-B7 ENQ STB M /52 PT IN B ST /50 SEND IDENTIFICATION CLOCK CIRCUIT ENQUIRY PAIENIEB 3.789.364

SHEET 1 or 5 IO OUTPUT I21 22 CIRCUIT KEYBOARD r/ KEYBOARD INTERFACE CLOCK I LOGIC RST PRINTER ENQ ENQ STB MEN-B7 /32 PT IN v E I/3O SEND IDENTIFICATION CLOCK CIRCUIT ENQUIRY FIG. I

Cv MONOSTABLE K FLIP FLOP 6 MULTIvIBRATORl FIG. 2A F I628 R LATCH 6 FIG.2C

ADDRESS CODE TERMINAL BACKGROUND OF THE INVENTION This invention relates to an identification circuit and more particularly an identification circuit for use in a remote unit which must identify itself to other remote units or to a central unit.

From the vast worldwide teletype network to a simple centralized terminal network, it sometimes is necessary that each machine identify itself whenever it is communicating with another machine or with the central unit. In the past, teletype machines have been primarily mechanical devices and the identification message transmission has been accomplished primarily by mechanical means. These mechanical means include a cylinder device having 2l rows of prongs extending therefrom where some of the prongs have been removed-in a programmed manner. Upon command, the cylinder device turns one revolution and the prongs interact with detector means which detect the programmed identification message. The message is then transmitted out by the teletype machine. Because an entire revolution of the cylinder is necessary, the transmitted message will always be 21 characters long, although in many instances, only a few characters of information need be sent. Further, it becomes very difficult to reprogram the cylinder if this ever becomes necessary. a

Modern technology has provided the nonmechanical teletype machines, such as the thermal printing device now in wide use. For these primarily nonmechanical devices, it is desirable to avoid the use of the mechanical cylinder described above. Further it is desirable to be able to provide an identification circuit which can be easily programmed and which can be easly reprogrammed, if necessary, directly at the point of use.

SUMMARY OF THE INVENTION In accordance with one preferred embodiment of this invention, there is provided identifying means associated with a remote unit for transmitting a coded identification signal identifying the remote unit. The coded signal includes a given number of N bit characters where the given number is between I and M. The identifying means comprises matrix means having N+1 columns and M rows. There is an intersection of each row and each column. Electrical connections are capable of being made between any of these intersections to cause a signal applied to a row to appear on a column. A first sub-matrix of N columns and M rows is assigned to develop the coded identifying signal and a second sub-matrix of one column and M rows is assigned to d evel? ope a stop signal. The identifying means further includes logic means for applying a signal to each of the matrix rows, one at a time. It also includes first means for providing as the coded identification signal the signals electrically appearing on the N columns of the first sub-matrix and second means responsive to one of either a signal appearing on to the one column of the second sub-matrix or Mth row of said matrix for providing a stop signal. The logic means further includes means responsive to the stop signal for causing the signal applied to the matrix rows to cease upon the occurrence of the stop signal.

FIG. 1 is a block diagram of a remote unit including the identification circuit of this invention;

FIGS. 2A, 2B and 2C show respective circuit blocks used in the block diagram showing the indentification circuit;

FIG. 3 is a block diagram of the identification circuit of the present invention;

FIG. 4 shows a series of waveforms useful in understanding the operation of the identification circuit shown in FIG. 3;

FIG. 5 is a perspective view of the portion of the printed circuit board having the matrix of the identifi- 5 cation circuit thereon; and

FIG. 6 is a plan view of the printed wiring on the printed circuit board of FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1, a block diagram of a remote unit, such as data terminal 10, is shown. Data terminal 10 includes keyboard 12, keyboard interface logic 14, printer 16, output circuit 18 and identification circuit 20. Keyboard 12 may be a state of the art alphanumeric keyboard which provides a seven bit code when one of the keys thereof (not shown) is depressed. A code such as ASCII may be employed for this purpose. In addition keyboard 12 will include a SEND key which maybe depressed prior to depressing the keys representing the message. I

The seven bit code, representing the depressed key, is applied, in parallel, over wires 22 to keyboard interface logic 14,' where it is processed by having a parity bit inserted and is serially sent over wire 24 to output circuit 18. Output circuit 18 then transmits the signal through wire 28 to the designated destination point, which may be another terminal (not shown) or a central unit (not shown). The signal from keyboard interface logic 14 is also sent in parallel over lines 26 (only one of which is shown) to printer 16 for causing the printing of a character manifested by the signal.

It is also possible for the central unit to poll data terminal 10. This may be accomplished by the central unit sending an ENQUIRY signal over line 28 to output circuit 18. Logic included within printer 16 decodes the ENQUIRY signal and provides an ENQUIRY flag signal to line 30 which is coupled to-identification circuit 20.

Whenever the SEND key of keyboard 12 is depreesed, a SEND signal will be applied through line 32 to identification circuit '20. Whenever identification circuit 20 receives either the SEND signal or the EN- QUIRY flag signal, it becomes active and transmits a logic 1 ENQ signal and a logic 1 PT IN signal to keyboard interface logic 14. After a short time it transmits the first seven bit character of the identification signal on lines Bl through B7 to keyboard interface logic 14 and a short time later, a logic I ENQ STB pulse signal is sent to keyboard interface logic 14. The seven bit code is operated upon in keyboard interface logic 14 in the same manner as the seven bit code from keyboard 12 and sent over lines 24'and 26 to the output circuit 18 and printer 16 respectively. In response to the first character being sent to keyboard interface logic l4, and RST signal is sent to identification circuit 20. The RST signal causes the second character of the identification signal and another ENQ STB pulse to be transmitted over lines B1 through B7. It should be noted that during this time, a clock signal is also being sent from keyboard interface logic 14 to identification circuit 20. After the entire identification message has been sent from identification circuit 20 to keyboard interface logic 14, the logic I ENQ and PT IN signals return to logic and normal operation resumes.

Referring now to FIG. 2A, thr e is shown a block 40 which is used to represent a flip-flop (F-F) circuit in FIG. 3. Flip-flop 40 has five inputs labeled S, J, C, K and R and two outputs labeled Q and 6. In the reset state of flip-flop 40, the Q output is at logic 0 (zero volts or ground potential) and the 6 output is at logic 1 (positive potential). Whenever the signal applied to the S input of flip-flop 40 goes from logic I to logic 0,-

the state of flip-flop 40 changes to the set state if not already there; that is, the Q output becomes logic I and the 6 output becomes logic 0. Similarly, when the signal applied to the R input goes from logic I to logic 0, the state of flip-flop 40 assumes the reset state, if not already there;.that is, the Q output becomes logic 0 and the 6 output becomes logic 1. It should be noted that both the S and the R inputs to flip-flop 40 are independent of any clock signal applied to flip-flop 40.

When a clock signal applied to the C input of flip-flop 40 becomes logic 1 while the J input is logic 1, flip-flop 40 will assume a set state on the rising edge of the clock pulse. Similarly, if the K input is logic 0, flip-flop 40 will assume the reset state upon the leading edge of the logic I clock pulse.

Referring now to FIG. 2B, the block diagram of the monostable multivibrator (M. M. V.) 42 is shown. Monostable multivibrator 42 includes S and 1 inputs and Q and 6 outputs. Whenever a logic 1 signal is applied to the S input of monostable multivibrator 42, the Q output goes from logic 0 tologic l for a predetermined fixed time and then returns to logicO and 6 output goes from logic I to logic 0 for that fixed time and then returns to logic 1. Monostable multivibrator 42 can be selected to respond to either the leading or trailing edge of the logic 1 signal. However ifa logic 0 is applied to the l input of monostable multivibrator 42, any change at the S input is ignored. The fixed time of the pulse at the Q output or the 6 output is controlled by the value of resistance (not shown) and capacitance (not shown) which is coupled to monostable multivibrator 42.

Referring now to FIG. 2C, a latch circuit 44 is shown which has S and R inputs and Q and 6 outputs. Whenever a signal goes from logic 0 to logic 1 at the S input, the Q output will simlarly go from logic 0 to logic 1, if not already there. Similarly, whenever the voltage at the R input goes from logic 0 to logic I, the 6 output goes from logic 1 to logic 0, if not already there.

Referring now to FIGS.3 and 4, a detailed block diagram of identification circuit 20 and waveforms useful in understanding that block diagram are shown. The heart of identification circuit 20 is a matrix 46 which has 21 rows labeled 1, 2, 3, i and 21 and eight columns labeled A, B, G, H. It is possible to have an electrical connection between any row and column intersection by inserting a conductor between a coupling terminal connected to a row, such as terminal 48, and a coupling terminal coupled to a column, such as terminal 50. The conductor'may be a diode which is poled to conduct from the column terminal 50 to the row terminal 48, such as diode 52. Each of the twentyone rows represent one character and each of the first seven columns A through G represent the individual bits of the character. The eighth column H is assigned to a stop bit, and a diode, such as diode 54, will couple the eighth column to the row manifesting the last character of the identification code.

Normally each row and each column are at a positive potential. However during the time the identification code is being transmitted, the rows are set to ground potential, one at a time, so any column of the matrix coupled through a diode to the ground potential row assumes ground potential. This ground potential is detected by the inverter gates 56, 58 59 coupled to the columns A through G and inverted to represent a logic 1 bit. In this manner whenever a logic I is desired, a diode is inserted, and whenever a logic 0 is desired, no diode is inserted.

The logic circuitry associated with matrix 46 will now be described with reference being invited to the waveforms shown in FIG. 4 to more easily follow the described operation. Upon application of power to identi fication circuit 20, upsequencing circuit 60 applies a 100 millisecond logic 0 reset pulse to the R inputs of printer inhibit flip-flop 62 and I. D. inhibit flip-flop 64 and through NAND gate 66 and inverter 68 to the R input of I. D. start flip-flop 70. As previously explained, a logic 0 applied to the R input of a flip-flop unconditionally resets the flip-flop and thus flip-flops 62, 64 and 70 are all reset. This is the initial condition which allows identification circuit 20 to properly respond to either the SEND signal or ENQUIRY flag signal.

The SEND signal and ENQUIRY flag signal are applied over lines 32 and 30 respectively to the two inputs of OR gate 72. The output of OR gate 72 is applied to the S input of I. D. state monostable-multivibrator 74. The IDSM signal is taken from the 6 output of l. D. start monostable multivibrator 74 and applied to the C input of I. D. start flip-flop 70. The IDSM signal is a 50 millisecond logic 0 pulse, and has a leading edge at the time of the leading edge of the ENQUIRY flag signal or SEND signal.

The trailing (rising) edge of the IDSM logic 0 pulse causes ID start flip-flop 70 to become set because the J and K inputs thereof are at logic I, or +V volts. At this time the IDSF signal at the Q output becomes logic 1 and the IDS? signal at the 6 output becomes logic 0. The logic 0 IDS I signal is applied to an enable (E) input of shift register 76 which will be described in detail hereinafter. The TITS? signal is applied to the S input of S. R. load monostable multivibrator 78 and to the R input of ENQ latch 80. The leading edge of the W signal applied to S. R. load monostable multivibrator 78 causes the SRT. signal at the 6 output thereof to become logic 0 for approximately 50 microseconds. The SRE signal is applied to the S input of ENQ latch 80 and the load (L) input of shift register 76.

The leading edge of the still signal sets ENQ latch 80, thereby causing the ENQ signal at the Q output thereof to become logic I and the EN6 signal at the 6 output thereof to become logic 0. The logic 0 EN6 signal is applied to the S input of printer inhibit flip-flop 62, thereby setting it and causing the 6 output thereof to become logic 0. This is the PT IN signal which applied to keyboard interface logic 14 in FIG. 1 to inhibit the printer from printing the identification code. In certain situations it may be desirable to have the printer print the identification code and in this event the PT IN signal may be disconnected from keyboard interface logic 14.

Also, the ENQ signal from ENQ latch 80 is applied to keyboard interface 14 shown in FIG. 1 to indicate that identification circuit will be transmitting information thereto and to cause the keys on keyboard 12 to be locked out. This condition will remain so long as the ENQ signal is logic 1. During this time the RST signal from keyboard interface logic 14 is logic 0. This signal is applied through inverter 81, where it becomes a logic 1 and then is applied to one input of NAND gate 82. The ENQ signal from ENQ latch 80 is applied to the other input of NAND gate 82. At the time the ENQ signal becomes logic 1, the output of NAND gate 82 becomes logic 0. This causes the S. R. clock monostable multivibrator 84 to be triggered, causing the Q ouput thereof, or SRC signal, to become logic 1 for approximately three microseconds and the 6 output, or W signal, to become logic 0 for about three microseconds. The SRC signal is applied to the clock (C) input of shift register 76 and this causes a logic 0 to be applied from the first stage of shift register 76 to the first row of matrix 46 as will be explained in more detail hereinafter. The SRC signal is applied through twenty microsecond delay circuit 86 to ENO STB monostable multi-vibrator 88, causing a 50 microsecond logic 0 pulse to be provided from the 6 output thereof as the ENQ STB signal. This signal is applied to keyboard interface logic 14.

Shift register 76 is a twenty-one flip-flop stage shift register which has the Q output of each stage coupled to a respective one of twenty-one rows of matrix 46.

shift register 76 becomes logic 0 shift register 76 is ready to be initially loaded. When the SRL signal applied to the load (L) input of shift register 76 becomes logic 0, and the first SRC logic 1 signal is applied to the clock input of shift register 76 the first stage of shift register 76 becomes reset and the second through twenty-first stages become set. Thus, after the SRC signal returns to logic 0, the first stage stores a logic 0 bit and the remaining stages store logic 1 bits. On each subsequent logic 1 SRC clock pulse, the logic 0 bit is shifted one stage towards the twenty-first stage. Thus after the first SRC logic 1 pulse, the first row of matrix 46 is at logic 0, or 0 volts.

Because only the Gth column of matrix 46 is coupled to the first row through diode 52, the B7 signal from the output of inverter 59 will be logic 1 and the B1 through B6 signals will be logic 0. The Bl through B7 signals are applied to the keyboard interface 14 shown in FIG. 1. After a delay caused by a delay circuit 86, the logic 0 ENQ STB signal is also applied to keyboard interface logic 14. During the time the ENQ STB signal is logic 0, the state of B1 through B7 signals is sampled in keyboard interface logic 14 and processed for transmission as the first identification code character.

After this occurs, keyboard interface logic 14 transmits a logic 1 RST signal to identification circuit 20. This signal is applied through inverter 81 and causes a logic 0 signal to be applied to NAND gate 82. This, in turn, causes the output of NAND gate 82 to become logic 1 for the duration of the RST signal. When the output from NAND gate 82 returns to logic 0, S. R. clock monostable multivibrator 84 is again triggered and a second logic 1 SRC pulse signal is provided to the clock input of shift register 76. This causes the second state to become reset, all others being set, thereby causing the logic 0 to be applied to the second row of matrix 46. Again the SRC signal is delayed by delay circuit 86 and the ENO STB signal is transmitted to keyboard interface logic 14 and the state of B1 through B7 signals is sampled. This represents the second character of the identification code signal.

The output of inverter 81 is also applied'to the S input of l. D. inhibit flip-flop 64 and one input of NAND gate 90. The other input of NAND gate 90 is coupled to the clock signal from keyboard interface logic 14. The duration of the RST signal is approximately one clock time. The leading edge of the logic 0 signal applied to the S input of l. D. inhibit flip-flop 64 causes it to assume the set state. It will remain set until the first clock pulse after the logic 0 at the S input is removed because the J and K inputs therof are at logic 0 (grounded). Thus, the ID lN signal at the 6 output of l. D. inhibit flip-flop 64 becomes logic 0 for two clock times. This logic 0 signal is applied to the inhibit input of I. D. start monostable multivibrator 74 to inhibit it from processing any further SEND or ENQUIRY signals during the time a character is being sent to keyboard interface logic 14. The 1D 1N signal is also applied to the clock input of printer inhibit flip-flop 62 and the J and R inputs thereof are set at logic 0.

When the keyboard interface logic 14 receives the second ENQ STB signal it sends another RST signal to interface circuit 20 and-the same events just described occur again. This continues until just prior to shift register 76 applying a logic 0 signal to the 1''" row of matrix 46. Diode 54 connects the 1" row to the 11" column. As previously explained, the l-l" column of matrix 46 is as? signed to a stop bit that is diode 54 placed to connect the 1'1" column to the i" row when the i" row contains the last character of the identification code. This causes the H" column of matrix 46 to become logic 0 when a logic 0 is applied to the i" row.

The H' column of matrix 46 is coupled to one input of NAND gate 92, and the other input of NAND gate 92 is coupled to the twenty-first row of matrix 46. Normally both of the inputs to NAND gate 92 are logic 1, so the output thereof, which is the STOP signal, is logic 0. However when the 11 column becomes logic 0, the output of NAND gate 92, and thus, the STOP signal, becomes logic 1. The STOP signal is applied as one input to NAND gate 94 and the second input of NAND gate 94 is coupled to the RST signal. When both the STOP signalandRST signal are logic 1, the output of NAND gate 94, which is the RST-STOP signal, becomes logic 0. The W is applied to one input of NAND gate 66, the other input thereof being logic 1 from upsequencing circuit 60. The logic 0 RST-STOP signal causes the output of NAND gate 66 to become logic 1 and this is inverted to logic 0 at the output of inverter 68. The logic 0 from inverter 68 is applied to the R input of l. D. start flip-flop 70 to reset it and cause the IDSF signal to become logic 0 and the lDSF signal to become logic 1. This, in turn, causes the ENQ latch to be reset and the ENQ signal becomes logic 0 and the m signal becomes logic 1. The logic 1 m thus allows the printerinhibit flip-flop 62 to be reset at the trailingedge of next lD 1N logic 0 signal from I. D. inhibit flip-flop 64. The logic 0 ENQ signal indicates to keyboard interface logic 14 that identification circuit 20 is finished sending the ientification code.

It should be noted that the twenty-first stage output of shift register 76 is coupled to the input of the first stage thereof. This is provided so that, if NAND gate 92 does not sense the logic .0 being applied to either the H". column or the twenty-first row, the logic is recirculated. In this manner, the logic 0 from shift register 76 is never lost.

Reference is now made to FIGS. and 6 in which FIG. 5 shows a perspective view of a portion of printed circuit board 100 upon which identification circuit may be constructed and specifically that portion having matrix 46 thereon and FIG. 6 shows a top plan view of printed circuit board 100 without various elements affixed thereto. Printed circuit board 100 may be a state of the art printed circuit board which includes a substrate 102 having a plurality of holes thereon and further having printed wiring, such as wire 104, connecting certain of the holes.

In FIG. 5, certain of the integrated circuit logic components such as 106, 108 and 110 are shown. These may be placed in any desired location on printer circuit 'board 100 and interconnected to form the circuit shown in FIG. 3. Also shown in FIG. 5 are sixteen strips, such as strips 1 12, 1 14, 1 16 and 118, which form the matrix 46. Each of the strips have twenty-one holes into which one end of a circuit element may be inserted. Each of the holes of alternate ones of the strips, such as strips 112 and 116, are connected to different rows of matrix 46. Each of the holes of the remaining strips, such as strips 114 and 118 are respectively connected to one of the columns of matrix 46, with all of the holes of strip 114 being connected to the first column, all of the holes of strip 118 being coupled to the second column, and so forth.

A connection between a row and a column may be made by inserting a diode between adjacent strips, such as inserting diode 120 between strips 112 and 114.

Diode 120 being inserted in the first holes of the strips 112 and 114 would thus connect the first column with the first row of matrix 46. If onedesired, for instance, to connect the second column with the third row, diode 122 would be inserted between strips 116 and 118 in the third holes from the top. If the message is only eight characters long, a diode 124 is inserted between strips 126 and 128 in the eighth holes from the top, as shown in FIG. 5.

The plan view of FIG. 6 is taken looking from the top in FIG. 5 with the circuit'components and strips removed. The solid lines such as lines 104, 130 and 132,

represent printed wiring and the broken lines, such as line 134, represent printed wiring on the opposite side of board 100. Printed circuit board 100 has sixteen columns, such as columns 136, 138, 140 and 142, with twenty-one holes in each column, such as holes 144,

146 and 148.,Each of the holes has printed wire around the inner circumference thereof, as indicated by the solid line thereat. The strip 112, shown in FIG. 5, is positioned on printed circuit board 100 so that the twenty-one holes thereof are in alignment with the twenty-one holes of column 136 and are electrically connected thereto by, for instance, soldering. Similarly the holes of strips 114, 116 and 118 are aligned with the holes of columns 138, 140, 142 of printed circuit board 100 and electrically connected thereto.

Each of the printed wires, such as wires and are connected to logic elements (not shown) which would correspond to the inverters 56, 58 and 60 shown in FIG. 3, Each of the printed wires such as wires 134 and 156 are connected to outputs of the shift register 76 of FIG. 3. Thus, to make the first row to first column connection, it is necessary to couple holes 146 and 148 together and this is accomplished by diode 120 shown in FIG. 5.

What is claimed is: I 1. Identifying means associated with=a remoteunit for causing said remote unit to transmit a coded identification signal identifying said remote unit, said coded signal including a given number of N bit characters, said given number being a number between one and M, said identifying means comprising:

matrix means having N+l columns and M rows, there being an intersection of each row and column, electrical connections being capable of being made between any of said intersections to cause a signal applied to a row to appear on a column, a first submatrix of N columns and M rows being assigned to develop said coded identification signal and a second submatrix of one column and M rows being assigned to develop a stop signal; logic means for applying a signalto each of said matrix rows, one at a time; first means for providing as the coded identification signal the signals appearing on the N columns of said first submatrix; and second means responsive to one of either a signal appearing on the one column of said second submatrix or the Mth row of said matrix for providing a.

stop signal, said logic means further including means responsive to said stop signal for causing said signals applied to said matrix rows to cease upon the occurrence of said stop signal.

2. The invention according to claim 1 wherein said logic means includes an M stage shift register means and clocking means, said shift register means shifting a row signal, one stage at a time, from said first stage towards said Mth stage each time said clocking means provides a clock signal thereto, each stage of said shift register means being coupled to a different one of said matrix rows. g

3. The invention according to claim 2:

wherein the signal applied to any given row of said matrix by said shift register means is applied to the selected columns by means of said electrical connections between the intersections of said given row and said selected columns; and

wherein said first meansfurther includes means for causing said remote unit to transmit the signals at each of said N columns as said coded identification signal.

4. The invention according to claim 2:

wherein said remote unit includes control means for providing first and second control signals, said first control signal causing said shift register means to apply said row signal to the first row of said matrx,

said control means, in response to a row signal being applied to any row of said matrix, providing said second control signal; and

wherein said clocking means responds to each secwhich are electrically coupled to the row then having the signal applied thereto, said logic means further including means responsive to the occurrence of a signal applied to said one column for causing ond control signal by providing a clock signal to 5 said signals applied to said row to cease, and said shift register means. means for providing as the address code the signals 5. The invention according to claim 4: appearing on the other ones of said columns. wherein said logic means further includes input logic 8. The invention according to claim 7:

responsive to said first control signal for causing wherein said matrix means includes 2(N+l) strips, the first stage of said shift register means to assume o each strip having M corresponding holes thereon, one state and the remaining stages of said shift regalternate ones of said strips having the holes ister means to assume a second state, and for prothereof electrically coupled together and the reviding a signal to enable said clocking means to remaining ones of said strips having each hole electrispond to said second control signal; and cally coupled to a different one of said rows; and wherein said logic means further includes means for wherein said electrical coupling means is inserted in providing a third control signal to said control corresponding holes of adjacent strips to electrimeans each time a clocking means signal is procally couple one row to one column. vided, said control means responding to said third 9. The invention according to claim 8: control signal by providing said second control sigwherein said matrix means is arranged on a printed nal. I circuit board having printed wiring on two sides 6. The invention according to claim 5: thereof and at least 2(N+l) columns of holes wherein said logic means further includes means to therethrough, each column of holes including at apply said stop signal to said input logic means; and least M corresponding holes, one side of said board wherein said input logic means further includes having M leads of printed wire, each of said M means for enabling said shift register means to shift leads being connected to corresponding holes of said row signal between the occurrence of said first alternate ones of said columns of holes, each of control signal and said stop signal. said M leads being coupled to said logic means, the 7. In a terminal which transmits a uniquely assigned other side of said board having N+l leads of terminal address code between one and M characters printed wire each of which connects the M holes of long, each character having N bits, programmable terone of the remaining columns, each said N+l leads minal address transmitting means comprising: being coupled to said logic means; and

a programmable M row by N 1 column matrix wherein each of said 2(N+l) strips is aligned with a means, said matrix means being programmable by different one of said 2(N+l) columns so that the the insertion of electrical coupling means between holes of said strip is electrically connected to a corselected row-column intersections, one of said colresponding hole of said board.

10. The invention according to claim 9 wherein said electrical coupling means are diodes poled to conduct current between said one and said other side of said board. 

1. Identifying means associated with a remote unit for causing said remote unit to transmit a coded identification signal identifying said remote unit, said coded signal including a given number of N bit characters, said given number being a number between one and M, said identifying means comprising: matrix means having N+1 columns and M rows, there being an intersection of each row and column, electrical connections being capable of being made between any of said Intersections to cause a signal applied to a row to appear on a column, a first submatrix of N columns and M rows being assigned to develop said coded identification signal and a second submatrix of one column and M rows being assigned to develop a stop signal; logic means for applying a signal to each of said matrix rows, one at a time; first means for providing as the coded identification signal the signals appearing on the N columns of said first submatrix; and second means responsive to one of either a signal appearing on the one column of said second submatrix or the Mth row of said matrix for providing a stop signal, said logic means further including means responsive to said stop signal for causing said signals applied to said matrix rows to cease upon the occurrence of said stop signal.
 2. The invention according to claim 1 wherein said logic means includes an M stage shift register means and clocking means, said shift register means shifting a row signal, one stage at a time, from said first stage towards said Mth stage each time said clocking means provides a clock signal thereto, each stage of said shift register means being coupled to a different one of said matrix rows.
 3. The invention according to claim 2: wherein the signal applied to any given row of said matrix by said shift register means is applied to the selected columns by means of said electrical connections between the intersections of said given row and said selected columns; and wherein said first means further includes means for causing said remote unit to transmit the signals at each of said N columns as said coded identification signal.
 4. The invention according to claim 2: wherein said remote unit includes control means for providing first and second control signals, said first control signal causing said shift register means to apply said row signal to the first row of said matrx, said control means, in response to a row signal being applied to any row of said matrix, providing said second control signal; and wherein said clocking means responds to each second control signal by providing a clock signal to said shift register means.
 5. The invention according to claim 4: wherein said logic means further includes input logic responsive to said first control signal for causing the first stage of said shift register means to assume one state and the remaining stages of said shift register means to assume a second state, and for providing a signal to enable said clocking means to respond to said second control signal; and wherein said logic means further includes means for providing a third control signal to said control means each time a clocking means signal is provided, said control means responding to said third control signal by providing said second control signal.
 6. The invention according to claim 5: wherein said logic means further includes means to apply said stop signal to said input logic means; and wherein said input logic means further includes means for enabling said shift register means to shift said row signal between the occurrence of said first control signal and said stop signal.
 7. In a terminal which transmits a uniquely assigned terminal address code between one and M characters long, each character having N bits, programmable terminal address transmitting means comprising: a programmable M row by N+1 column matrix means, said matrix means being programmable by the insertion of electrical coupling means between selected row-column intersections, one of said columns being assigned to a stop code and other ones of said columns being assigned to said address code; logic means for applying a signal to said rows one at a time, said signal being applied to those columns which are electrically coupled to the row then having the signal applied thereto, said logic means further including means responsive to the occurrence of a signal applied to said one column for causing saiD signals applied to said row to cease, and means for providing as the address code the signals appearing on the other ones of said columns.
 8. The invention according to claim 7: wherein said matrix means includes 2(N+1) strips, each strip having M corresponding holes thereon, alternate ones of said strips having the holes thereof electrically coupled together and the remaining ones of said strips having each hole electrically coupled to a different one of said rows; and wherein said electrical coupling means is inserted in corresponding holes of adjacent strips to electrically couple one row to one column.
 9. The invention according to claim 8: wherein said matrix means is arranged on a printed circuit board having printed wiring on two sides thereof and at least 2(N+1) columns of holes therethrough, each column of holes including at least M corresponding holes, one side of said board having M leads of printed wire, each of said M leads being connected to corresponding holes of alternate ones of said columns of holes, each of said M leads being coupled to said logic means, the other side of said board having N+1 leads of printed wire each of which connects the M holes of one of the remaining columns, each said N+1 leads being coupled to said logic means; and wherein each of said 2(N+1) strips is aligned with a different one of said 2(N+1) columns so that the holes of said strip is electrically connected to a corresponding hole of said board.
 10. The invention according to claim 9 wherein said electrical coupling means are diodes poled to conduct current between said one and said other side of said board. 